1. Field of the Invention
The present invention relates to an optical communication module that packages a photoelectric device, such as a laser diode and/or photodiode for performing optical communication.
2. Description of Related Art
Conventionally, the optical communication has become widespread, which utilizes an optical fiber and the like. The optical communication is performed with a light emitter, such as a laser diode, converting an electrical signal into an optical signal, with an optical fiber through which the optical signal is transmitted, and with a light receiver, such as a photodiode, converting the received optical signal into the electrical signal. Thus, it is well known to utilize an optical communication module that packages the photoelectric conversion devices, such as the laser diode and/or the photodiode, together with a peripheral circuit element for operating the photoelectric conversion device in the optical communication module depending on circumstances. Such an optical communication module is called as the optical sub-assembly (OSA). Recently, several inventions are reported for the optical communication and the optical communication module.
For example, Patent Document 1 proposes to utilize a configuration in which an output of a first photodiode for receiving light and an output of a second photodiode shielded from light are respectively input into differential amplifiers through gain control amplifiers, and a lowpass filter is arranged between an output terminal of an optical power detecting unit that detects an optical power and a gain control terminal of the gain control amplifier, for implementing an optical detector that can be applied to a high-speed and dynamic-range communication.
In addition, Patent Document 2 proposes an optical reception apparatus that can control adequately the amount of operating current/voltage and reduce the electrical power consumption, with a configuration in which a photodiode for receiving a signal, a photodiode for detecting an optical level, a signal amplifier that amplifies a received signal and a bias current control unit that controls a bias current provided to the signal amplifier are mounted on a single board, and the bias current control unit makes the signal amplifier operate when the signal current output from the photodiode for detecting the optical level is equal to or more than a predetermined value. In that optical reception apparatus, the photodiode for receiving the signal further includes a photosensitive area formed in a substantial circular shape smaller than the diffusion of the optical signal, and the photodiode for detecting the optical level further includes a photosensitive area that surrounds the photosensitive area of the photodiode for receiving the signal, for efficiently detecting the optical signal and enhancing the reception ability.
The inventions according to Patent Documents 1 and 2 relate to a peripheral circuit of a photoelectric conversion device, and expect to enhance the ability of the optical communication lead by the modification of the peripheral circuit. The inventions according to Patent Documents 1 and 2 utilize an optical communication module in which the board mounting the photoelectric conversion device and the peripheral circuit is fixed to a lead frame and sealed by resin to form a molded part, and a hemisphere lens is arranged on the surface of the molded part. This optical communication module is configured to make the lens arranged opposite to an exit terminal of the optical fiber.
Patent Document 3 proposes a light-electric conversion module excelling in the high frequency characteristic and being downsized, as the module includes: a photoelectric device that sends and receives optical signals; a stem that fixes the photoelectric device; a cap that covers the photoelectric device; and plural leads that apply electrical signals to the photoelectric device or transfer the electrical signals sent from the photoelectric device, wherein a plane portion is arranged on one end of a predetermined lead in the package configured with the stem and cap, and an electrical circuit component is arranged on the plane portion, one end of the electrical circuit connected to the photoelectric device, and the other end of the electrical circuit connected to the lead.
Patent Document 4 proposes an optical device module that makes the circuit component on the circuit board and the like operate a light source and/or optical detector, as the module includes: the light source and/or optical detector; a first package having a first surface with an opened portion for passing the optical signal and the second surface opposed to the first surface; a second package having an opened portion to accommodate a circuit board and the like and arranged perpendicular to the second surface of the first package; a leadframe that mechanically connects the first package and second package, and electrically connects the light source and/or optical detector of the first package with a contact point exposed in the opened portion of the second package, wherein an accommodated part, such as the circuit board, is mechanically connected with the second package and electrically connected with the contact point in the opened portion. In this optical device module, a lens block holding a lens is fixed to the first package, and an optical fiber is fit into the opened portion of the lens block.
Patent Document 5 proposes a method for manufacturing a leadframe connector utilized to connect an optical subassembly with a PCB (printed circuit board) of the optical communication module. In this method, a shape of a conductive portion is punched on a conductive ribbon, the conductive portion is bent appropriately, the open reel system is utilized for forming a case that insulates the conductive portion through the injection molding process, and then the conductive ribbon is cut to form each of manufactured leadframe connectors. The plural conductive portions in the single case can be electrically separated by penetrating the connected potion through the hole formed on the case.
3. Prior Art Document    Patent Document 1: Japanese Patent Application Laid-Open No. 2006-40976    Patent Document 2: International Publication No. WO 01/015348    Patent Document 3: Japanese Patent Application Laid-Open No. 2005-167189    Patent Document 4: U.S. Pat. No. 7,455,463    Patent Document 5: U.S. Pat. No. 7,370,414